The present invention is an improvement upon the invention disclosed in U.S. Pat. No. 6,983,785, issued on Jan. 10, 2006, and titled DOOR OPERATING MECHANISM AND METHOD OF USING THE SAME, which is hereby incorporated in its entirety by reference.
Most systems for operating garage doors utilize torsion springs to assist in lifting the garage door. Such torsion-spring-based systems function as follows. A shaft is normally located above the door opening. A pair of door drums are attached to the shaft. Cables connect the door drums to the garage door. As the garage door is raised, the cables wind around the drums; as the door is lowered, those cables unwind. A torsion spring is positioned along the shaft. One end of the torsion spring is connected to the shaft and the opposite end of the spring is anchored to the door opening. The torsion spring is preloaded during the installation process. This preloading provides the necessary torque to counterbalance or offset the torque that the garage door imposes on the shaft by its connection to the door drums. When the garage door is raised, the shaft rotates in a first direction, and the torsion spring releases stored energy, thus assisting in lifting the door. When the door is lowered, the shaft rotates in the opposite direction, and the torsion spring is reloaded with energy, thereby, assisting in offsetting the weight of the door and slowing its decent.
However, the use of torsion springs to assist in the lifting and lowering of garage doors offers disadvantages. For example, since torsion springs must be preloaded at installation, a technician performing that installation is exposed to risk of injury. If the technician overloads the torsion spring or the torsion spring includes a material defect, the spring may fail suddenly. Due to the preload, such a failure of a spring is unpredictable and may cause the spring to strike the technician or a garage surface with great force, causing significant bodily injury or property damage. In addition, the very process of preloading a torsion spring is difficult and laborious, and many individuals are physically incapable of completing such a task. Therefore, there is a need to replace torsion springs commonly used for garage door mechanisms with safer and easier apparatus and methods.
U.S. Pat. No. 6,983,785 discloses the use of gas springs as an alternative to torsion springs. A gas spring is fixed at one end and slideably mounted along a track on the opposite end. A cable connects the gas spring to a side drum, which is attached to the shaft above the garage door. As the door is lowered, the cable winds around the side drum, causing the gas spring to compress and store energy. This compression serves to counterbalance the weight of the door and slow the decent of the door. As the door is raised, the compressed gas spring extends and releases energy, pulling the cable attached to the side drum and assisting in lifting the door.
The present invention provides alternatives to the use of torsion springs in assisting the operation of a garage door. The elimination of torsion springs overcomes disadvantages in the prior art. In addition, the present invention provides for novel arrangements of apparatus and methods for using these alternatives to torsion springs.